Recently, the efficacy for health and the medical efficacy of a water (hydrogen water) comprising hydrogen molecules in a large amount have been attracting attention. As the method for generating hydrogen water, there have been known, for example, a method based on the electrolysis of water and a method dissolving hydrogen gas in water; various apparatuses for generating electrolyzed water have been proposed as the apparatus for generating hydrogen water by electrolysis. For example, there has been proposed an electrolysis apparatus for generating an electrolyzed negative electrode water comprising hydrogen gas (H2) and reducing ions wherein an electrolyzer having a porous diaphragm is used, electrodes, namely a positive electrode and a negative electrode are inserted into an aqueous electrolyte solution, a direct current is made to flow and ions were moved (see Patent Literature 1). There has been proposed an apparatus for generating electrolyzed water by arranging an anode and a cathode so as to face each other in an electrolyzer and by electrolyzing raw water (aqueous sodium chloride solution or desalted water) between both electrodes, wherein the substrate used is made of porous titanium having in a high porosity the pores through which electrolytic ions generated by the electrolysis of the raw water pass and being highly frequently brought into contact with electrolytic ions, and an electrode prepared by plating the surface of the substrate with platinum or a platinum-series noble metal as a metallic body is adopted as the anode (see Patent Literature 2).
However, the apparatus described in Patent Document 1 is an apparatus for electrolyzing pure water with an electrolyte added thereto, and finds difficulty in generating hydrogen water by electrolyzing the water filtered with, for example, a reverse osmosis membrane. Patent Document 2 describes an apparatus for generating electrolyzed water in which the arrangement of a porous anode, a cathode and a diaphragm is variously varied, and describes the electrolysis of aqueous sodium chloride solution or a desalted water between both electrodes. However, these apparatus mainly aims at obtaining an electrolyzed water comprising hypochlorous acid or an electrolyzed water comprising ozone using a porous anode, but does not aim at obtaining hydrogen water having a high concentration. Recently, hydrogen water servers are installed at homes, offices and others, drinking of hydrogen water comes off; thus, apparatuses for generating electrolyzed water capable of being incorporated in limited spaces within the servers have been demanded. However, when the areas of the electrodes are reduced in order to incorporate the apparatus within a limited space, there occurs a problem that no highly-concentrated hydrogen water can be obtained. Moreover, when electrodes and an ion-exchange membrane are incorporated in a small space, the temperature of water or the like flowing in the electrodes, the ion-exchange membrane and the apparatus increases during operation of the apparatus, and hence there occurs a problem of reduction of the dissolved-hydrogen amount due to the gasification of hydrogen or the breakage of the ion-exchange membrane. In addition, in an apparatus for generating electrolyzed water, it is important to reduce the areas or the number of the electrode plates, and to suppress the influence of the temperature increase, without being limited to the case of the installation of the apparatus for producing electrolyzed water within a server. The conventional apparatuses for generating electrolyzed water, including the above-described apparatuses are all far from solving these problems.